The present invention relates to a process supplying, simultaneously and under the best economic conditions, energy sources, soft water and at least one by-product, from aqueous substances and an energy source, in which the aqueous substance is brought to boiling point in a sealed enclosure provided with means for supplying the aqueous substances and means for recovering the steam and the residue from evaporation, the steam produced is fed under pressure into a turbine of a turbo-alternator for producing electricity, the water vapor leaving the turbine is condensed into soft water, for use as drinking water, water for domestic purposes, or water for sprinkling or in irrigation, and the residue of the evaporation of the aqueous substance is recovered as a by-product.